The rate of oxidative quenching of 3C60 by chloranil (CA) in CH2Cl2 is much enhanced by added trifluoroacetic acid (TFA) or hexafluoro-2-propanol (HFIPA). These additives have similar hydrogen-bonding powers but differ widely in their proton acidities. In both cases, quenching rate constants calculated for H-bonded CA increase sharply with additive concentration. H-bonded clusters around the quinone are postulated in which electron transfer is coupled to fast protonation of CA-• by TFA, and strong H-bonding or solvation of charged radicals by HFIPA. This is consistent with observed neutral semiquinone formation, higher radical yields, and much slower back reactions for TFA. The C60+• spectrum (ε = 25 000 ± 2000 M-1 s-1 at 980 nm) shows low absorption throughout the visible region. Charge-shift reactions of C60+• and arenes follow Rehm-Weller-Marcus kinetics and afford efficient preparation of arene+• cation radicals using visible light.
|Number of pages||6|
|Journal||Journal of Physical Chemistry A|
|Publication status||Published - Dec 13 2001|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry